In the oil and gas industry, wells are drilled into the earth to reach reservoirs of hydrocarbons buried deep within the ground. In drilling, servicing, and completing wellbores, so-called pipe strings are utilized. Pipe strings, including drill strings, casing strings, tool strings, etc. are made up of lengths of threadedly connected pipe sections joined end to end to reach the potentially great depths of wellbores. As an example, in a drilling operation, the drill string may include a bottomhole assembly (BHA) which may include a drill bit, mud motor, and a measurement while drilling (MWD) sensor array, as well as various other sensors, spacers and communications apparatuses.
As drilling progresses deeper into the Earth, lengths of drilling pipe are added at the top of the drilling string. Generally, two or three 30 foot lengths of drilling pipe are connected into so-called pipe stands prior to being added to the drilling string. The drilling rig hangs the drilling string on a pipe slips and disconnects the drilling string from the drawworks. The drilling rig lifts the next pipe stand above the drilling string with the drawworks and threadedly connects it to the drilling string using, in some instances, an automated or “iron” roughneck to, among other things, reduce personnel exposed to potentially dangerous environments on the drilling floor.
At times, the entire tubular string must be removed from the wellbore. Such a “tripping out” operation may be required if, for example, a drill bit breaks, a tool lowered into the wellbore must be returned to the surface, or a wellbore reaches its target depth. At times, the same or a new tubular string must be run back into the wellbore. Such a “tripping in” operation may, for example, put the drill string with new drill bit back into the well, lower a downhole tool such as a packer, or insert a casing string into the wellbore to complete the well.
Since modern wells may become extremely deep, tripping out or tripping in operations may require a large number of threaded pipe joints to be disconnected (broken out) or connected (made up). Traditionally, the same drawworks, roughneck, and slips are used to make or break each connection. As the operation of a drilling rig can be extremely expensive, the need to trip in or trip out a tubular string may be a very costly operation. Additionally, damage may be caused to the wellbore simply by removing the tubular string from or inserting the tubular string into the wellbore. For instance, wellbore pressure may, in some circumstances, be rapidly increased or decreased by a rapid movement of a downhole tool. Commonly referred to as “swabbing”, these pressure fluctuations may cause, for example, reservoir fluids to flow into the wellbore or may cause instability in a formation surrounding a wellbore.